Hall-effect sensor having integrally molded frame with printed conductor thereon

ABSTRACT

A Hall-effect sensor, wherein a Hall element is disposed in a magnetic path being formed by a magnet and a flux guide, and the magnet, flux guide, and Hall element are integrally held with a molded frame, and the Hall element is fixed to the magnet (or flux guide) or the molded frame. This Hall-effect sensor can easily position the Hall element with higher sensitivity.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a Hall-effect sensor, for example, foruse in detecting a crank angle for an ignition timing control apparatusfor an internal combustion engine.

2. Description of Related Art

Recently, the Hall effect has been used for such various types ofsensors as a position sensor, an angle sensor, and a speed sensor. Assuch a type of sensor using the Hall effect, there is well known aHall-effect sensor in which a Hall element, a peripheral circuit such asan amplifier, a waveform shaping circuit, a surge protection element,and a magnetic circuit for generating a magnetic flux are integrallyprovided with each other by a resin. In addition to it, there is alsowell known a Hall IC in which a Hall element is fitted in a hybridintegrated circuit on a substrate made of ceramics. When suchconventional Hall-effect sensors are manufactured, each of the Hallelement, parts of the magnetic circuit and the like are positioned byuse of jigs first, and then, a thermoplastic resin or a thermosettingresin is poured into a space surrounding each of them, following whichbeing dried or hardened by a heater. As a result, there exist someproblems that it is necessary to provide a lot of jigs for positioningsuch Hall element and parts in the sensor, that the positioning accuracyof those Hall element and parts is not so high that the sensor is notsuitable for mass production, and that sensitivity of the sensor isinferior.

SUMMARY OF THE INVENTION

The foregoing problems are solved in accordance with the presentinvention. The Hall-effect sensor of the present invention comprisesflux generating means for generating a magnetic flux and forming amagnetic path, a Hall element being disposed in this magnetic path, anda molded frame which holds both of the flux generating means and theHall element integrally, the Hall element being fixed to the fluxgenerating means or to the molded frame. A printed conductor forfetching a signal is also formed on the flux generating means or on themolded frame, and this printed conductor is electrically connected tothe Hall element by connecting means. As a material for the connectingmeans, a bonding wire, solder or the like can be employed. The fluxgenerating means concretely has a magnet and a flux guide, and it isdesirable that this flux generating means forms a magnetic path bytransmitting a magnetic flux being generated by the magnet to the fluxguide. If the flux generating means is conductive, the Hall element isfixed to the flux generating means with an insulative film therebetween.

The Hall element may be a bare Hall chip, and the Hall chip may be aHall IC, in which the Hall element is provided with a part of aperipheral circuit.

The Hall-effect sensor of the present invention can be used as aposition sensor or a speed sensor, as well as an angle sensor fordetecting a crank angle for ignition timing control for an internalcombustion engine.

It is an object of the present invention to provide a Hall-effect sensorwhich can readily position the Hall element.

It is another object of the present invention to provide a Hall-effectsensor which has higher sensitivity.

It is a further object of the present invention to provide a Hall-effectsensor whose parts can readily and automatically be assembled.

The above and further objects and features of the invention will morefully be apparent from the following detailed description taken with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of a Hall-effect sensor of a first embodimentof the present invention,

FIG. 2 is a sectional view for explaining the functional operation ofthe first embodiment shown in FIG. 1,

FIG. 3 is a plan view showing a flux shutter being used in embodimentsof the present invention,

FIG. 4 is a sectional view of a Hall-effect sensor of one transformedexample of the first embodiment of the present invention,

FIG. 5 is a sectional view of a Hall-effect sensor of a secondembodiment of the present invention,

FIG. 6 is a sectional view of a Hall-effect sensor of one transformedexample of the second embodiment of the present invention,

FIG. 7 is a sectional view of a Hall-effect sensor of anothertransformed example of the second embodiment of the present invention,

FIG. 8 is a sectional view of a Hall-effect sensor of a furthertransformed example of the second embodiment of the present invention,

FIG. 9 is a sectional view of a Hall-effect sensor of a still furthertransformed example of the second embodiment of the present invention,

FIG. 10 is a sectional view of a Hall-effect sensor of a thirdembodiment of the present invention, and

FIG. 11 is a sectional view of the Hall-effect sensor in FIG. 10 acrossline XI--XI.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Now, embodiments of the present invention will be described below withreference to the accompanying drawings. In each of such embodiments aswill be described below, there will be described a sensor for detectinga crank angle of an internal combustion engine.

FIRST EMBODIMENT

In FIG. 1, reference numeral 1 designates a flux generating member(magnet), which has a N pole and a S pole as shown in the figure. Ontothe magnet 1, there is formed an insulative film 5 by means ofevaporation, application or the like. On the insulative film 5, there isformed a printed conductor 7 with a predetermined pattern. There isarranged a Hall element 2 in a position above the magnet 1. The Hallelement 2 is electrically connected to the printed conductor 7 by asoldering paste 4. As the Hall element 2, a bare Hall chip or a Hall ICmay be employed, either of which being called the Hall element in thisspecification. There is provided such an electronic part 6 as a surgeprotection element on the insulative film 5 by the soldering paste 4.Such members constituting the sensor such as the magnet 1, insulativefilm 5, printed conductor 7, Hall element 2, soldering paste 4, andelectronic part 6 are surrounded with a molded frame 3 made of a moldresin.

Reference numeral 20 designates a flux shutter as shown in FIG. 3. Thisflux shutter 20 is a magnetic material of a disk form, in which each ofplural vanes 21 is provided to have a predetermined angle of radiation.When the flux shutter 20 is rotated around an axis O of rotation, thevane 21 and a space 22 which is defined in between the vanes move byturns in a position above the Hall element 2. When such a Hall-effectsensor as shown in FIG. 1 is employed as a crank angle sensor forinternal combustion engine, the flux shutter 20 is rotated insynchronism with rotation of an internal combustion engine.

Now will be described below the operation of the sensor. When the space22 of the flux shutter 20 is positioned above the Hall element 2 asshown in FIG. 1, a magnetic flux being generated by the magnet 1 formssuch a magnetic path as shown by the broken line A. The magnetic fluxbeing exerted upon the Hall element 2, thus is in the small state. Onthe other hand, when the vane 21 of the flux shutter 20 is positionedabove the Hall element 2 as shown in FIG. 2, a magnetic flux beinggenerated by the magnet 1 forms such a magnetic path as shown by thebroken line B. The magnetic flux being exerted upon the Hall element 2,thus is in the large state. As can be seen from the above, such changeof the magnetic flux in synchronism with the rotation of the internalcombustion engine is given to the Hall element 2, and an electric signalcorresponding to the change of the magnetic flux is generated accordingto the Hall effect. This electric signal is led to an outside circuit(not shown) via the printed conductor 7, and its waveform is processedso as to be used for detecting a crank angle.

FIG. 4 shows another example of the first embodiment. In the figure,reference numeral 1 designates a flux generating member, which iscomprised of a magnet 11, a flux guide 12 kept in contact with themagnet 11, and a flux guide 13 which is positioned to face in oppositedirections of the magnet 11 and the flux guide 12 with a gap 8 between.A pole P₁ of the flux guide 12 and a pole P₂ of the magnet 11 which hasa function opposite to the pole P₁ are arranged in the same direction.Portions of the flux guide 13 shown by 13a and 13b are positioned toface in opposite directions of the poles P₁ of the flux guide 12 and theP₂ of the magnet 11, respectively. This facing portion 13a is formed asone bent-end portion of the flux guide 13, and so is the facing portion13b as a plane portion of the flux guide 13. There is applied theinsulative film 5 onto the facing portion 13b. The flux guide 13 isprovided with an insert conductor 23 for fetching an electric signalconverted by the Hall element 2 to the outside, both of which areintegrally formed with each other. The printed conductor 7 with apredetermined pattern is provided on the insulative film 5 and theinsert conductor 23. This printed conductor 7 is electrically connectedto the Hall element 2 by a lead wire 9 of the Hall element 2. There isprovided an electronic part 6 such as a surge protection element on theinsulative film 5 with the printed conductor 7 between. Members such asthe flux generating member 1 and the Hall element 2 are integrally heldby a molded frame 3 made of a mold resin. An end of the insert conductor23 is projected from the molded frame 3 to be a connection pin 24. Atone end of the molded frame 3, there is formed a connector 25 whichconnects the sensor to equipment and the like. When the mold is formedin this embodiment, after such each member such as the magnet 11, theflux guide 12, and the flux guide 13 to which the Hall element 2 isfixed are positioned, the molded frame 3 is adapted to be formed.

The operation of the sensor will be described below. Such a flux shutter20 as shown in FIG. 3 moves in the gap 8. When the vane 21 of the fluxshutter 20 is positioned in the gap 8, a magnetic flux being generatedby the magnet 11 is shortened by the vane 21, and there is formed amagnetic path extending from the pole P₁ through the vane 21, pole P₂,magnet 11, flux guide 12, to the pole P₁. The magnetic flux exerted uponthe Hall element 2, thus is in the small state. On the other hand, whenthe space 22 of the flux shutter 20 is positioned in the gap 8, amagnetic flux being generated by the magnet 11 is not shortened, andthere is formed a magnetic path extending from the pole P₁ through thefacing portion 13a, flux guide 13, facing portion 13b, Hall element 2,pole P₂, magnet 11, flux guide 12, to the pole P₁. The magnetic flux toexert upon the Hall element 2, then, is in the large state. As can beseen from the above, such change of the magnetic flux in synchronismwith rotation of the internal combustion engine is given to the Hallelement 2, and an electric signal corresponding to the change of themagnetic flux is generated according to the Hall effect. This electricsignal is led to the outside circuit (not shown) via the printedconductor 7 and the insert conductor 23, and its waveform is processedto be used for detecting a crank angle.

As described above, in the first embodiment, the Hall element 2 isdirectly fixed to the flux generating member 1 (magnet 11 or flux guide13), and it is not necessary to provide a jig for positioning the Hallelement 2. When the Hall element 2 is fixed to the flux generatingmember 1 (magnet 1 or flux guide 13), such an art as packaging a circuitelement onto a printed wiring board is employed, and thus higherpositioning accuracy of the Hall element can be obtained. Additionally,the number of parts to be used for the sensor can be reduced, andassembly of the parts can easily be carried out. The sensor, then, canhave higher sensitivity and the parts thereof can readily andautomatically be assembled.

The insulative film 5 has been applied onto a surface of the magnet 1 orflux guide 13 in this embodiment, however, if the magnet 1 or the fluxguide 13 is insulative, there is no need to apply the insulative film 5thereon. It is not intended that the material of the insulative film 5be limited, and resin, glass, or ceramics such as alumina are suitable.

SECOND EMBODIMENT

FIG. 5 shows a sensor of the second embodiment. Reference numeral 1 inthe figure shows a flux generating member which is comprised of a magnet11 and a flux guide 12 which is kept in contact with the magnet 11. Theflux generating member 1 is integrally locked to a molded frame 3 madeof a mold resin. The molded frame 3 has a fixing portion 34 for fixingthe Hall element 2. In the molded frame 3, there is fitted an insertconductor 23, which is connected to a printed conductor 7 being formedon the fixing portion 34 in the molded frame 3. At one end of the moldedframe 3, there is formed a connector 25. The Hall element 2 is disposedin a position below the magnet 11 with a gap 8 between. A lead wire 9 ofthe Hall element 2 is electrically connected to the printed conductor 7and to the insert conductor 23 by a soldering paste 4. An electronicpart 6 such as a surge protection element is provided in the fixingportion 34 of the molded frame 3 with the soldering paste 4 between. Anepoxy resin is filled in a space surrounding the Hall element 2 and theelectronic part 6. When a temperature circumstance is severe, a silicongel is filled in the space and a cover (a cover 32 as shown in FIGS. 10,11) is provided in order to protect both of them.

Hereinbelow will be described the operation of the sensor. Such a fluxshutter 20 as shown in FIG. 3 moves in the gap 8 in synchronism withrotation of an internal combustion engine. When the space 22 of the fluxshutter 20 is positioned in the gap 8, a magnetic flux being generatedby the magnetic 11 forms such a magnet path as shown by the broken lineA. The magnetic flux being exerted upon the Hall element 2, thus is inthe large state. On the other hand, when the vane 21 of the flux shutter20 is positioned in the gap 8, a magnetic flux being generated by themagnet 11 forms such a magnetic path as shown by the broken line B. Themagnetic flux exerted upon the Hall element 2, thus is in the smallstate. As can be seen from the above, such change of the magnetic fluxin synchronism with the rotation of the internal combustion engine isgiven to the Hall element 2, and an electric signal corresponding to thechange of the magnetic flux is generated according to the Hall effect.This electric signal is led to the outside circuit (not shown) via theprinted conductor 7 and the insert conductor 23, and its waveform isprocessed to be used for detecting a crank angle.

FIG. 6 shows a transformed example of the sensor of the secondembodiment. As similar to the embodiment shown in FIG. 4, a flux guide13, in this example, is provided so as to be in contact with a Hallelement 2 and is fixed to the molded frame 3, which fixing is not shownin detail in the figure. The Hall element 2 is housed in a hole 26,which is formed to be through a fixing portion 34 of the molded frame 3.Other construction of this sensor being the same as that in FIG. 5,explanation of those elements numbered identically with those of theembodiment of FIG. 5 will be omitted here.

Hereinbelow will be described the operation of the sensor. When thespace 22 of the flux shutter 20 is positioned in the gap 8, such amagnetic path as shown by the broken line A is formed and the magneticflux exerted upon the Hall element 2 is in the large state. On the otherhand, when the vane 21 of the flux shutter 20 is positioned in the gap8, such a magnetic path as shown by the broken line B is formed and themagnetic flux exerted upon the Hall element 2 is in the small state. Ascan be seen from the above, such change of the magnetic flux insynchronism with rotation of the internal combustion engine is given tothe Hall element 2, and an electric signal corresponding to the changeof the magnetic flux is generated according to the Hall effect. Thiselectric signal is led to the outside circuit (not shown) via theprinted conductor 7 and the insert conductor 23, and its waveform isprocessed to be used for detecting a crank angle.

In such a transformed example as shown in FIG. 6, because there isprovided the flux guide 13, a flux density for the Hall element 2 can bemade to be larger in the magnetic path shown by the broken line A.Accordingly, the change of the magnetic flux for the Hall element 2 canbe made to be larger when the flux shutter 20 moves. Additionally, theHall element 2 is housed in the hole 26 in order to shorten the magneticpath in the gap 8, and thus detecting sensitivity of the sensor cangreatly be improved. Moreover a signal accuracy against a change oftemperature or voltage can be increased.

FIG. 7 shows another transformed example of the sensor of the secondembodiment. In this example, a Hall element 2 of a Hall IC chip (flipchip) is electrically connected to a printed conductor 7 by a solderingbump 27. In this example, a substrate made of epoxy or alumina on whichthe Hall element 2 and the electronic part 6 are installed is needless.Accordingly, the magnetic path in the gap 8 is short, detectingsensitivity of the sensor can be improved in the same way as the exampleshown in FIG. 6. Other construction and operation of this sensor beingthe same as those of the sensor shown in FIG. 6, explanation of thoseelements numbered identically with those of the sensor in FIG. 6 will beomitted here.

FIG. 8 shows a further transformed example of the second embodiment. Asthe same as the embodiment shown in FIG. 7, a Hall element 2, in thisexample, is a Hall IC chip. The Hall element 2 is connected to a printedconductor 7, and so is the printed conductor 7 to an insert conductor 23by a bonding wire 30, respectively, and the Hall element 2 iselectrically connected to the insert conductor 23. Other constructionbeing the same as the example shown in FIG. 7, explanation of thoseelements numbered identically with those of the embodiment in FIG. 7will be omitted here. And an operation of this example is the same asthat shown in FIG. 6.

FIG. 9 shows a still further transformed example of the secondembodiment. A Hall element 2, in this example, is a Hall IC. The Hallelement 2 has a composition that a plurality of electronic parts and aprinted circuit are provided onto a ceramic substrate 28. The Hallelement 2 is provided with a plurality of terminal electrodes 29. Eachterminal electrode 29 is connected to an insert conductor 23 by abonding wire 30. As a suitable material for the bonding wire 30, gold,copper, aluminum, or alloy may be employed. Other construction andoperation being the same as the sensor in another example of the secondembodiment, explanation of those elements numbered identically withthose of the sensor of another example will be omitted here.

In the second embodiment, the Hall element 2 being directly fixed to themolded frame 3, it is not necessary to provide a jig for positioning theHall element 2. When the Hall element 2 is fixed to the molded frame 3,such an art as packaging a circuit element onto a printed wiring boardis employed, and the sensor can position the Hall element with higheraccuracy. Additionally, if an engaging projection and the like areformed in a fixing position for the Hall element 2 in the molded frame 3in advance, for example, the Hall element 2 can readily be positionedwith greater accuracy. Additionally, the number of parts to be used inthe sensor can be reduced, and those parts can easily be assembled.Additionally, a sensor with greater sensitivity can be provided andparts of the sensor can readily and automatically be assembled.Furthermore, when the Hall element 2 is electrically connected to theinsert conductor 23 by the bonding wire 30, it is not necessary toprovide soldering. It is possible to provide a sensor which is resistantto mechanical vibration, and in which deformations of the printedconductor 7 and the insert conductor 23 according to expansion orcontraction thereof on the basis of temperature change of the moldedframe 3 are generated.

THIRD EMBODIMENT

FIGS. 10 and 11 show the third embodiment. In those figures, referencenumeral 1 designates a flux generating member which is comprised of amagnet 11, a flux guide 12, a a flux guide 13. This flux generatingmember 1 is integrally positioned and locked in a molded frame 3. Themolded frame 3 has a locking portion 3a for a plate 31, a lockingportion 3b for the flux generating member 1 (flux guide 12), and ahousing portion 3c for a Hall element 2 and the like. An insertconductor 23 is fitted in the molded frame 3, and at one end of themolded frame 3, there is formed a connector 25. The plate 31 made ofmetal, plastic or the like is arranged in a position to face the magnet11 with a gap 8 between and is locked to the locking portion 3a. On theother surface of the plate 31 which is not facing the magnet 11, thereis applied an insulative film 5, onto which is formed a printedconductor 7. The Hall element 2 and such an electronic part 6 as a surgeprotection element are connected to the printed conductor 7 by asoldering bump 27. The printed conductor 7 is electrically connected tothe insert conductor 23 by a bonding wire 30. The flux guide 12 ispositioned and locked in the locking portion 3b of the molded frame 3.The flux guide 13 is firmly fixed to a cover 32 by an adhesive agent 33.The cover 32 for covering the housing portion 3c is fixed to the moldedframe 3. A resin such as a silicon gel is filled into a spacesurrounding the Hall element 2 and the flux guide 13 in the housingportion 3c in order to protect both of them from their surroundings.

Hereinbelow will be described the operation of the sensor. Such a fluxshutter 20 as shown in FIG. 3 moves in the gap 8 in synchronism withrotation of the internal combustion engine. When the space 22 of theflux shutter 20 is positioned in the gap 8, a magnetic flux beinggenerated by the magnet 11 forms such a magnetic path as shown by thebroken line A in FIG. 11. The magnetic flux exerted upon the Hallelement 2 thus is in the large state. On the other hand, when the vane21 of the flux shutter 20 is positioned in the gap 8, a magnetic fluxbeing generated by the magnet 11 forms such a magnetic path as shown bythe broken line B in FIG. 11. The magnetic flux exerted upon the Hallelement 2 thus is in the small state. As can be seen from the above,such change of the magnetic flux in synchronism with the rotation of theinternal combustion engine is given to the Hall element 2, and anelectric signal corresponding to the change of the magnetic flux isgenerated according to the Hall effect. This electric signal is led tothe outside circuit (not shown) through the insert conductor 23, and itswaveform is processed to be used for detecting a crank angle.

In the third embodiment, the Hall element 2 is positioned and fixed tothe molded frame 3 via the plate 31, then, it is not necessary toprovide a jig for positioning the Hall element 2. The Hall element 2 ispositioned by being fixed to the soldering bump 27. This fixing canreadily be carried out with higher positioning accuracy with an assemblyrobot, for example. The molded frame 3 has a limit size of thickness. Inthe third embodiment, the plate 31 made of metal or plastic is used, itis easy to make the plate 31 thin, so the magnetic path in the gap 8 canbe short. As a result, it can be realized to provide a sensor withhigher sensitivity and automatic assembly of the parts can easily beperformed.

The insulative film 5 and the printed conductor 7 are formed on theplate 31 in the third embodiment, however, those may not necessarily beformed. When an insulative material is used for the material of theplate 31, it is not necessary to apply the insulative film 5, and inaddition, when a Hall IC is used as the a Hall element 2, it is notnecessary to provide the printed conductor 7, either.

In such embodiments as mentioned above, explanation has been made forwhen the sensor is used so as to detect a crank angle for ignitiontiming control for internal combustion engine. However, the sensor maybe employed as other sensors such as a position sensor or a speedsensor. In addition, the flux shutter 20 may not be adapted to berotated but may be adapted to be moved linearly. It is not intended thatconfiguration of the flux shutter 20 be limited to that shown in FIG. 3.

As this invention may be embodied in several forms without departingfrom the spirit of essential characteristics thereof, the presentembodiment is therefore illustrative and not restrictive, since thescope of the invention is defined by the appended claims rather than bythe description preceding them, and all changes that fall within themetes and bounds of the claims, or equivalence of such metes and boundsthereof are therefore intended to be embraced by the claims.

What is claimed is:
 1. A Hall-effect sensor, comprising:flux generatingmeans for generating a magnetic flux, a Hall element disposed in thepath of said magnetic flux, positioning and fixing means for positioningand fixing said Hall element and holding said flux generating means andsaid Hall element integrally therewith, said positioning and fixingmeans comprising a molded frame having a fixing portion, wherein saidfixing portion is formed in advance in said molded frame, a printedconductor being formed on said fixing portion of said molded frame, aninsert conductor fitted within said molded frame and coupled to saidfixing portion of said molded frame and arranged to receive an outputsignal from said Hall element, and a peripheral circuit means positionedin said fixing portion of said molded frame, said peripheral circuitmeans performing an electronic function for said Hall element and beingfixed to said printed conductor to be connected to said Hall element,said Hall element being fixed to said fixing portion and connected tosaid printed conductor.
 2. A Hall-effect sensor as set forth in claim 1,further comprising:connecting means for electrically connecting saidHall element to said printed conductor, wherein said connecting meansare positioned between said Hall element and said printed conductor. 3.A Hall-effect sensor as set forth in claim 2, wherein said connectingmeans is a bonding wire.
 4. A Hall-effect sensor as set forth in claim2, wherein said connecting means is solder.
 5. A Hall-effect sensor asset forth in claim 1, wherein said flux generating means has a magnetfor generating a magnetic flux and a flux guide for transmitting thegenerated magnetic flux.
 6. A Hall-effect sensor as set forth in claim1, wherein said Hall element is a bare Hall chip.
 7. A Hall-effectsensor as set forth in claim 6, wherein said Hall chip is a Hall IC.